In recent years, there have been widely used non-contact IC tag which is fitted to to-be-controlled persons or goods (adherends) for control of distribution, etc. of such persons or goods. This IC tag can store data in the IC chip built therein. Further, since the IC tag can communicate in non-contact with an interrogator, the stored data for control in the IC chip can be exchanged with the interrogator.
As the application fields of IC tag, there are various fields, for example, communication tickets for transport, control of incoming or outgoing of persons in business firms, etc., personal certification, inventory control of goods, logistics, etc. IC tags of various forms are being used so as to match respective application fields.
IC tag is fitted to, for example, a commodity and is placed in stores together with the commodity. When the commodity has been sold, the data stored in the IC chip of IC tag is read by an interrogator. With the read data, the physical distribution of the commodity is controlled.
In order to conduct the above-mentioned various controls accurately using an IC tag, the reliability of the circuit board constituting the IC tag is very important.
The circuit board of IC tag comprises an insulating substrate (e.g. a synthetic resin film) and various conductor patterns (e.g. electronic circuits) formed thereon. These conductor patterns are electrically connected to each other by using a conductive material to form a jumper(s), in some cases. In such cases, each jumper is formed on the upper part of the other conductor patterns. Therefore, in order to prevent the electrical conduction between the jumper and the other conductor patterns, an insulating layer is beforehand formed between them.
The jumper is formed on a complex structure consisting of an insulating substrate, conductor patterns, an insulating layer, etc. Therefore, there is a case that the conduction of the jumper is deteriorated with the passage of time.
There is described, in Patent Literature 1, a circuit board having a structure enabling the measurement of the conduction of jumper, in order to confirm the quality of produced circuit board. In this circuit board, there is provided, in the insulating layer covering the upper side of each conductor pattern, an opening which reaches the conductor pattern, and the conduction of jumper can be measured utilizing the opening. However, this circuit board is not constituted in order to allow the jumper to have stable conduction. The circuit board is constituted so that the quality of produced circuit board can be confirmed.
Patent Literature 1: JP-2005-72458A ([0053])